Question

Write the chemical equation of the reaction of glucose with bromine water.

Hint:

Bromine water oxidises only aldehydes (–CHO) to acids but does not oxidise ketones.

Answer 1

Step 1: Nature of glucose.
Glucose is an aldohexose and contains an aldehyde group (–CHO). Bromine water is a mild oxidising agent. Step 2: Reaction.
Bromine water oxidises the –CHO group of glucose to –COOH, forming gluconic acid. \[ C_6H_{12}O_6 \,(Glucose) + Br_2 + H_2O \;\longrightarrow\; C_6H_{12}O_7 \,(Gluconic \, acid) + 2HBr \] Step 3: Observation.
The reddish-brown colour of bromine water disappears, confirming the presence of the aldehyde group in glucose. Conclusion:
Glucose reacts with bromine water to form gluconic acid, showing that glucose contains an aldehyde group.